'\" te
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.TH DDI_GET_INSTANCE 9F "Jan 16, 2006"
.SH NAME
ddi_get_instance \- get device instance number
.SH SYNOPSIS
.nf
#include <sys/ddi.h>
#include <sys/sunddi.h>



\fBint\fR \fBddi_get_instance\fR(\fBdev_info_t *\fR\fIdip\fR);
.fi

.SH INTERFACE LEVEL
illumos DDI specific (illumos DDI).
.SH PARAMETERS
.ne 2
.na
\fB\fIdip\fR\fR
.ad
.RS 7n
Pointer to \fBdev_info\fR structure.
.RE

.SH DESCRIPTION
The \fBddi_get_instance()\fR function returns the instance number of the device
corresponding to \fIdip\fR.
.sp
.LP
The system assigns an instance number to every device.  Instance numbers  for
devices attached to the same driver are unique.  This provides a way for the
system and the driver to uniquely identify one or more devices of the same
type. The instance number is derived by the system from different properties
for different device types in an implementation specific manner.
.sp
.LP
Once an instance number has been assigned to a device, it will remain the same
even across reconfigurations and reboots. Therefore, instance numbers seen by a
driver may not appear to be in consecutive order. For example, if device
\fBfoo0\fR has been assigned an instance number of \fB0\fR and device
\fBfoo1\fR has been assigned an instance number of \fB1\fR, if \fBfoo0\fR is
removed, \fBfoo1\fR will continue to be associated with instance number \fB1\fR
(even though \fBfoo1\fR is now the only device of its type on the system).
.SH RETURN VALUES
The \fBddi_get_instance()\fR function returns the instance number of the device
corresponding to \fIdip\fR.
.SH CONTEXT
The \fBddi_get_instance()\fR function can be called from user, interrupt, or
kernel context.
.SH SEE ALSO
.BR path_to_inst (5)
.sp
.LP
\fIWriting Device Drivers\fR
